Conversion of hydrocarbons in the presence of a hydrogenated donor diluent



March 1, 1966 w. F- AREY, JR., ETAL 3,238,118

CONVERSION OF HYDROCARBONS IN THE PRESENCE OF A HYDROGENATED DONORDILUENT Filed Nov. 6, 1962 FRACTIONATOR |4 48 H NAPHTHA 2 I 52 NAPHTHA26 3 44 I2 I 28 46 PRooucT GAS on. I 38 FRACTIONATOR FEED, SEPARATOR lHYDROCRACKER IO sz L ,62 1-8 63 GAS HYDROCRACKATE BOTTOMS ASH L66 -54 3472 THERMAL CONVERSION r ZONE COKE William F. Arey, J I Ralph BurgessMason nvemors I s fivy? Potent Ahornev United States Patent CONVERSIONOF HYISROCARBONS IN THE PRES- ENCE OF A HYDROGENATED DONOR DILUENTWilliam Floyd Arey, Jr., Baton Rouge, and Ralph Burgess Mason, DenhamSprings, La., assignors to Esso Research and Engineering Company, acorporation of Delaware Filed Nov. 6, 1962, Ser. No. 235,732 Claims.(Cl. 20859) This invention relates to the conversion of high boilinghydrocarbon oils to lower boiling hydrocarbons. More particularly, theinvention relates to the conversion of crude petroleum oil or residualfractions thereof to naphtha in an integrated process involvinghydrocracking of a gas oil fraction and conversion of the high boilingresidue to suitable hydrocracking feed in a non-catalytic thermal stepusing the hydrocrackate bottoms as a solvent and hydrogen donor.

Hydrocarbon conversion processes are known where a relatively highboiling aromatic compound is partially hydrogenated to form a hydrogendonor which is then used in a hydrogen exchange step. Following thehydrogen exchange step the spent donor is rehydrogenated partially andreused in another hydrogen exchange step. Crude oil contains ash and ifthe crude oil as such is catalytically hydrocracked, the catalystbecomes deactivated by the ash components. The present inventiondiscloses an integrated process for treating whole petroleum crude oilor residual fractions thereof to produce ash-free gas oil forhydrocracking. The crude oil is fractionated and .the separated gas oilfraction is hydrocrack-ed. Hydrocracked products are fractionated andthe hydrocrackate bottoms are mixed with the crude residue and treatedin a thermal non-catalytic conversion step to upgrade the residue andalso produce a better gas oil feed for hydrocracking.

The present invention is especially adapted for the treatment andconversion of crude petroleum oils in which a gas oil fraction separatedfrom the crude oil is hydrocracked, and the hydrocrackate bottomsseparated from the hydrocracked products are used as a hydrogen donor inthe HDDC thermal conversion of the residual oil fraction separated fromthe crude oil in a non-catalytic thermal conversion. The thermallyconverted products may be separately fractionated but are preferablycombined with the whole petroleum crude oil feed and fractionated. Thecrude oil is preferably a naphthenic crude.

More specifically, the crude petroleum oil and thermally cracked orconverted products are fractionated or separated into a naphthafraction, a gas oil fraction for hydrocracking, and a bottoms fraction.Hydrocrackate bottoms containing hydrogen donor diluent formed duringhydrocracking are mixed with the crude oil bottoms fraction and passedto the thermal non-catalytic HDDC conversion zone or reactor. Theproducts from the thermal reactor are combined with the original crudeoil feed and fractionated as just described. This provides a recycle ofthe unconverted crude oil bottoms to the thermal reactor to convert thebot-toms to lower boiling hydrocarbons.

The thermal conversion step is conducted at a temperature in the rangebetween about 700 and 1000 F. and at a pressure in the range betweenabout 200 and 2000 p.s.i.g. The flow rate of total oil feed in thethermal converter is between about 0.25 and 10 v./v./hr. Internalrecycle of the higher boiling components can be achieved by control ofthe temperature and pressure so that some of the product is withdrawn asa vapor phase from the thermal converter. The solvent action of the hy-3,238,118 Patented Mar. 1, 1966 drogen donor in the thermal conversionzone prevents or minimizes deposition of poly condensed aromatichydrocarbons in the thermal conversion zone or hydrogen exchange zoneand hence a minimum amount of coke is made in the thermal conversionzone.

Normally an ash concentration builds up in the thermal conversion zoneresulting from a concentration of ash in the residual or bottomsfraction from the crude oil fractionator. The quantity of ash ismaintained within bounds and at a low level by a purge or by withdrawinga portion of the bottoms fraction, filtering or separating the ash, andreturning the treated bottoms to the thermal conversion zone.

The drawing represents a diagrammatic showing of apparatus adapted forcarrying out the process of the present invention.

Referring now to the drawing, the reference character 10 designates aline for feeding whole crude petroleum oil to a crude fractionator 12.The crude is preheated to a temperature between about 600 F. and 800 F.before introduction into tower 12, and in the tower is fractionated orsegregated into a plurality of fractions. Hydrocarbon gases and lowboiling hydrocarbons boiling up to about 180 F. pass overhead throughline 14. This overhead fraction may be treated to separate low boilinghydrocarbons from gases, if desired.

A naphtha fraction is Withdrawn as a top side stream through line 16.This naphtha fraction forms an excellent hydroforming feed. A higher andnarrow boiling naphtha boiling between about 375 and 430 F. can bewithdrawn as a side stream lower down the tower 12 through line 18, andprovision is made for separate withdrawal of this stream from theprocess through line 22 or for combining it with the naphtha side streamin line 16 by passing it through line 24.

Further down the crude fractionating tower 12 a gas oil fraction boilingbetween about 430 and 650 F. or up to about 1000 F. is withdrawn throughline 26 and hydrocracked in hydrocracking zone 28 presently to bedescribed in greater detail. Crude oil bottoms boiling above about theend point of the gas oil fraction are withdrawn from the bottom of crudetower 12 through line 32 for further treatment in a thermalnon-catalytic HDDC conversion zone 34 to be later described in greaterdetail. The products from this thermal conversion step are combined withthe feed in line 10 as will be hereinafter described.

Returning now to the hydrocracking step, the gas oil fraction withdrawnthrough line 26 is heated :to a temperature between about 550 F. and 850F., and under a pressure between about 500 and 2500 p.s.i.g., and passedthrough the hydrocracking zone 28 at a feed rate between about 0.4 and 4v./v./hr. The gas oil fraction contains virgin and recycled constituentsand condensed ring naphthenes or aromatic-naphthenic molecules hav ing afew aromatic nuclei with attached naphthenic or partially hydrogenatedring structures. The gas oil fraction itself contains hydrogen donordiluent precursors which have the ability to readily take up hydrogen inthe hydrocracking zone, and to release it in the thermal noncatalyticthermal HDDC zone 34. Hence, it is not necessary to add a hydrogen donordiluent from an extraneous source .to the gas oil feed going to thehydrocracking zone 28. The catalyst may be any suitable hydrocrackingcatalyst, such as nickel sulfide on silicaalumina, a noble metal such asplatinum or palladium on a molecular sieve base having uniform poreopenings between about 6 and 15 angstrom units, noble metal onsilica-alumina, and various catalysts comprising Group VI and VIIImetals, oxides and sulfides on suitable supports such as silica-alumina,clays, etc.

Hydrogen is introduced into hydrocracking zone 28 through line 36 and isintroduced in an amount between about 500 and 20,000 s.c.f./b. of gasoil feed introduced into the hydrocracking reactor 28. The hydrogenshould through line 64, heated and passed to the thermal noncatalyticconversion zone 34. A portion of the hydrocrackate bottoms may bewithdrawn from the process through line 63, if desired or if necessary,to adjust the be at least 70% by volume pure. 5 ratio of hydrocrackatebottoms to crude residual oil. It is generally preferred to operate thehydrocracking The hydrocrackate bottoms have a boiling range abovereactor 28 in the range between about 20 and 70% conabout 430 F. Thehydrocrackate bottoms and crude version to 430 F. and lighter, but thisis governed by residual oil are mixed in a weight ratio between aboutthe amount of gas oil feed available and the amount of 0.3/1 to 4/1 ofbottoms to residual oil. hydrocrackate bottoms required for recycle. Thehydro- In the thermal conversion zone 34, the temperature is crackateproducts are withdrawn from the hydrocracking maintained between about700 F. and 1000 F. to crack zone 28 through line 37, are cooled andpassed to a gashigher boiling hydrocarbons in the crude residual oil toliquid separator 38 to separate hydrogen-containing gas naphthahydrocarbons, gas, and to upgrade the crude from liquid. The gas ispassed overhead and recycled to residual oil with the production of asmall amount of the hydrocracking zone 28 through line 36. Preferablycoke. Also, hydrogen exchange occurs between the residthe gas is treatedin a conventional manner (not shown) ual oil and the hydrocrackatebottoms by the release of to concentrate the hydrogen in the gas to berecycled to hydrogen from the hydrogen donor diluent to produce at least70% by volume of hydrogen, and also to remove from the residual oillower boiling hydrocarbons includany impurities such as sulfur ornitrogen compounds. ing additional gas oil feed for the hydrocrackingzone 28. Make-up hydrogen is introduced into line 36 as desired Thehydrocrackate bottoms act as a hydrogen donor and through line 42. as adiluent and solvent to reduce the production of coke The separatedliquid from separator 38 is passed during the non-catalytic thermalconversion in zone 34. through line 44 to product fractionator 46wherein it is Gases including C minus hydrocarbons are withdrawnfractionated into several fractions including a light fracoverheadthrough line 66 from zone 34, and if desired, tion boiling up to about180 F. and including C minus the small amount of coke made may bewithdrawn gas which passes overhead through line 48. This overthroughbottom line 68. The normally liquid fraction head fraction may befurther treated to separate low boiling above about C hydrocarbons iswithdrawn boiling hydrocarbons, if desired. A light naphtha fracthroughline 72 which discharges into feed line 10* to the tion boiling betweenabout 180 F. and 375 F. may be crude fractionator 12. In thefractionator 12 the thermalwithdrawn as a top side stream through line52 and may ly converted products are fractionated into the separate becombined with the light naphtha fraction withdrawn fractions abovedescribed in connection with tower 12, from the crude tower 12 throughline 16 to form a hydroand so additional naphtha and gas oil areproduced for forming feed. further processing as desired and essentiallyall of the Further down in second or product tower 46, a higher r crudeoil is converted to naphtha, and gas, with only a boiling narrow cutnaphtha boiling between about 375 30 small coke make. F. and 430 F. iswithdrawn through line 54 as a side Accumulation of ash in the cruderesidue bottoms in stream which may be withdrawn as such through 56 orline 32 is minimized by withdrawal or purging at intervals passedthrough line 58 and combined with the side stream from line 32 throughwithdrawal line 74. Instead of withdrawn through line 52. withdrawingcoke through line 68, the small quantities The hydrocracking in the zone28 is carried out under of coke made may be removed with the liquidpurge conditions and at a selected conversion to produce a hythroughline 74. drocrackate bottoms boiling above about 430 F. and In aspecific example for converting West Texas crude having more than about20 vol. percent of condensed ring oil, about 10,000 barrels of wholepetroleum crude oil naphthenes. feed per day plus 10,885 barrels per dayof recycle from Hydrocracking conditions for accomplishing this purline72 are passed through line 10 at a temperature of pose will depend uponthe nature of the feed and the about 750 F. and introduced into crudetower 12 where catalyst employed. In general, pressures greater than themixture is fractionated into gas, naphtha, gas oil, and 800 p.s.i.g. andtemperatures less than 800 F. are emcrude oil bottoms. About 860 barrels(liquid) per day ployed. As the naphthene content of the hydrocrackateof butane and higher hydrocarbons boiling up to about bottoms varieswith conversion, the feed rate is chosen 180 F. pass overhead throughline 14. About 2900 to limit the conversion to less than 70% andpreferably barrels per day of naphtha boiling between about 180 to lessthan so that the volume percent of con- F. and 430 F. are withdrawn as aside stream through densed ring naphthenes is more than about 20. Theline 16. This naphtha is preferably hydroformed to proeffect ofconversion on condensed ring naphthene content 55 duce high octanegasoline. About 12,050 barrels per day is shown in the following TableI. of gas oil boiling between about 430 F. and 1000 F.

TABLE I Feed boiling range, F 430-650 430-850 Hydrocracking conversion,vol.

percent- ()(Feed) 25 45 74 20 47 72 Hydrocracking conditions"Temperature, F 575 710 713 766 775 775 Pressuro,p.s.i.g 1,500 1, 5001,510 1, 500 1,500 1,500 Feed rate, v./v./hr 3.0 4. 0 2.7 0. 54 0.5 0.4Gas rate, s.c.f./b 6,700 6,000 7,700 6,000 0, 000 6,000 Vol. percentcondensed ring naphthenes. 20 30 27 20 31 27 20 The above Table I showsthat the conversion should be are withdrawn through line 26 as a sidestream as feed kept below so as to maintain a desired amount of 70 tothe hydrocracking zone 28. About 5075 barrels per condensed ringnaphthenes or partially hydrogenated condensed ring naphthenes.

The hydrocrackate bottoms are withdrawn through line 62, combined withthe residual or crude oil bottoms in day of crude residue and recycleare withdrawn from the bottom of crude tower 12 through line 32.

In the hydrocracking zone 28 the temperature is maintained at about 650F. and the pressure at about 1500 line 32 from crude tower 12, and themixture passed 75 p.s.i.g. About 8000 s.c.f/b. of feed ofhydrogen-contain ing gas are introduced into hydrocracking zone 28. Thecatalyst is a hydrocracking catalyst containing about 0.5% palladium ona zeolitic molecular sieve base having pore openings of uniform sizebetween about 6 and angstrom units as described in 'Gladrow et al.Patent No. 2,971,904, granted Feb. 14, 1961. The conversion to 430 F.minus is about 58%.

About 13,275 barrels per day of hydrocrackate product leavehydrocracking zone 28 (after hydrogen removal in separator 38) and passthrough line 44 into product fractionator 46 where the hydrocrackateproducts are fractionated into C minus hydrocarbon gas, hydrocrackatenaphtha and hydrocrackate bottoms. About 730,000 cubic feet per day of Cminus hydrocarbons are taken overhead through line 48. About 8200barrels per day of hydrocrackate naphtha consisting of butane and liquidhydrocarbon-s, boiling up to 430 F., are withdrawn through line 52 as aside stream and none withdrawn through line 54. This stream may befurther fractionated into components that may be blended directly intomotor gasoline. The heavier portion, i.e., 200-375 F. boling material,is preferably hydroformed.

Hydrocrackate bottoms in the amount of about 5,075 barrels per day arewithdrawn through line 62. These bottoms have a boiling point range ofbetwen about 430 F. and 1000 F. and contain about 25% by volume ofarcmatic hydrocarbons, about 35% by volume by naphthenes, and about 40%by volume of acylic paraffins. These hydrocrackate bottoms are mixedwith the crude residual and recycle :from line 32, and the mixturepassed through thermal non-catalytic conversion zone 34 where it ismaintained at a temperature of about 770 F. and a pressure of about 400p.s.i.g. The v./v./hr. flow rate of oil feed is about 1, consequentlythe time of heating is one hour in zone 34.

The converted products leaving the conversion zone 34 comprise about670,000 cubic feet per day of C minus gas, about 25 tons per day of coke(or 1.5 weight percent on crude feed), and about 10,885 barrels per dayof converted hydrocarbons containing mostly naphtha and gas oil withsome components boiling above about 1000 F. which are recycled tothermal conversion zone 34.

From the actual numbers given it will be seen that more volumes ofliquid hydrocarbons leave zone 34 through line 72 than enter zone 34through 64. The gas oil hydrocrackate feed is substantially free of ashand therefore hydrocracking catalyst in hydrocracking zone 28 is notdeactivated by ash components.

Based on 10,000 barrels per day of whole West Texas crude, the yieldsfrom the present process are as follows:

' Virgin and thermal naphtha b./d 3,760 Hydrocrackate naphtha b./d 8,200Total naphtha b./d 11,960 C minus gas s.c.f./d 1,300,000 Coke ton-s 25Data are also included showing the hydrocnacking conversion of virgingas oil from South Louisiana crude oil with 0.5% palladium on a zeoliticmolecular sieve having uniform pore sizes between 6 and 15 angstromunits. The pressure was about 100.0 p.s.i.g.

These data show good conversion and also show that a variation inconversion can be achieved by adjusting the operating conditions(temperature, feed rate, etc.). It is generally preferred to operate theprocess in the range of 4060% conversion to 430 F. minus, but this 6 isgoverened by the amount of gas oil feed available and the amount ofhydrocrackate bottoms required for recycle.

Additional data are included to show results obtained in treating anmixture of a vacuum residuum having a gravity of 7 API and boiling aboveabout 1000 F., and a hydrocrackate bottoms having an API gravity of 35and obtained from hydrocracking a South Louisiana virgin gas oil boilingbetween about 430 F. and 850 F. The mixture was in a 50/50 volume ratio.The mixture was heated for about 1 hour in a stirred autoclave at 755 F.and at autogenic pressure.

Product yields are as follows:

The feed for the above data consisted of a 1/ 1 volume ratio, thus thecoke make shown amounts to 2.9 wt. percent of the residuum portion ofthe feed. This is considerably lower than the 7% obtained by thermallyconverting the residuum to the same extent in the absence of thehydrocrackate bottoms as diluent and hydrogen donor.

The conversion of residuum may vary between about 40 and In the exampleof the large unit of 10,000 barrels of fresh crude feed per day, theconversion of residuum to material boiling below 1000 F. in the thermalconversion zone 34 is maintained to give 65% conversion of 1000 F.residuum and this requires a 58% conversion of 430 F.+ to 430 F. in thehydrocracking zone 28 to maintain a 1 to 1 ratio of hydrocrackatebottoms to residual feed for the thermal zone 34. The quantities of thevarious products vary with the different feeds. The hydrocracking zone82 may be operated at a lower conversion by Withdrawing some of thehydrocrackate bottoms for specialty uses such as diesel and jet fuel orheating oil. Also, the hydrocrackate bottoms-residiuum ratio can beincreased so as to further reduce the coke made in the thermalconversion zone 34.

By integration of the hydrocracking of distillate and the thermalhydrogen transfer conversion of the residual to distillate, essentiallyall of the whose crude petroleum oil can be converted to naphtha.

Catalyst contamination is avoided by employing a noncatalytic conversionof the residuum to distillate of low ash content. Carrying out thisconversion in the presence of the hydrocrackate bottoms as a hydrogendonor allows high conversion of the residuum with only a slight cokemake.

The integration of the thermal conversion and the hydrocracking stepprovides utilization of the available hydrogen in the donor diluentwhich would be a debit to the hydrocracking step alone.

The quantity of ash material in line 32 is maintained Within bounds bypurging through line 74 as needed or by withdrawing a portion of thestream through line 74 or line 68 from thermal conversion zone 34,filtering or centrifuging or the like to remove solids containingvanadium and nickel compounds, etc., and returning the oil filtrate tothe thermal conversion zone 34 or to tower 12. The amount of ashfiltered or centrifuged may be kept at a minimum by providing a settlingzone ahead of the filter to settle out most of the solids from the oil.The efiiciency of the settler may be enhanced by incorporating thehydrogen donor diluent with the material purged or removed through line74 or line 68. The recovered solids may be reworked to recover variousmetals such as vanadium, nickel etc.

What is claimed is:

l. A method of treating whole petroleum crude oils to recover lowerboiling hydrocarbons which comprises fractionating a whole petroleumcrude oil into a gas oil fraction and a bottoms residue, catalyticallyhydrocracking the gas oil fraction to produce lower boiling hydrocarbonsand higher boiling hydrogenated donor diluents, fractionating thehydrocrackate product into naphtha and hydrocrackate bottoms containinghydrogenated donor diluents, mixing the hydrocrackate bottoms with thebottoms residue and maintaining the mixture under superatmosphericpressure at an elevated temperature in a thermal non-catalytic HDDCconversion zone to effect hydrogen transfer and upgrading of saidbottoms residue to naphtha and gas oil and fractionating the productsfrom said thermal conversion zone to recover additional gas oildistillate and naphtha.

2. A method of treating whole petroleum crude oil which comprisesfractionating a whole crude oil combined with thermally convertedproducts as hereinafter produced into a gas oil fraction containingvirgin and treated components and a bottoms crude residue, catalyticallyhydrocracking said gas oil fraction at a temperature between about 550"F. and 850 F. in the range of below about 70% conversion to 430 F. minusto produce hydrocrackate bottoms having more than about 20 volumepercent of condensed ring naphthenes, separating naphtha andhydrocrackate bottoms from the hydrocrackate product, mixing at leastpart of the hydrocrackate bottoms with the bottoms crude residue andsubjecting the mixture to an elevated temperature in a thermalnon-catalytic HDDC conversion zone to effect conversion of about 40 to80% of the bottoms crude residue to naphtha and gas oil, recycling theproducts from said thermal conversion zone to said whole crudefractionation step as the thermally converted products above referred toand recovering additional gas oil feed for said hydrocracking step.

3. A method of treating whole petroleum crude oils to recover lowerboiling hydrocarbons which comprises fractionating a whole petroleumcrude oil into a gas oil fraction containing condensed ring aromaticsand a bottoms residue, catalytically hydrocracking the gas oil fractionto produce lower boiling hydrocarbons and to partially hydrogenate thecondensed ring aromatics to hydrogen donor diluents, fractionating thehydrocrackate product into naphtha and hydrocrackate bottoms containingthe hydrogen donor diluents, mixing the hydrocrackate bottoms with thebottoms residue and maintaining the mixture under superatmosphericpressure at an elevated temperature in a thermal non-catalytic HDDCconversion zone to effect hydrogen transfer and upgrading of bottomsresidue to naptht-ha and gas oil and recycling the products from saidthermal conversion zone to said whole crude oil fractionation step torecover additional naphtha and gas oil feed.

4. A method of treating whole petroleum crude oil which comprisesfractionating a whole crude oil combined with thermally convertedproducts as hereinafter produced into a gas oil fraction containingvirgin and treated components and a bottoms crude residue, catalyticallyhydrocracking said gas oil fraction at a temperature between about 550F. and 850 F. in the range of below about 60% conversion to 430 F. minusto produce lower boiling hydrocarbons and hydrogen donor diluentcompounds boiling above about 430 F., separating naphtha andhydrocrackate bottoms boiling above about 430 F. and contain-inghydrogen donor diluent compounds from the hydrocrackate product, mixingat least part of the hydrocrackate bottoms with the bottoms cruderesidue and subjecting the mixture to an elevated temperature in athermal non-catalytic HDDC conversion zone to effect conversion of thebottoms crude residue to naphtha and gas oil, recycling the productsfrom said thermal conversion zone to said whole crude fractionation stepas the thermally converted products above referred to and recoveringadditional gas oil feed for said hydrocracking step.

5. A method according to claim 3 wherein the weight ratio ofhydrocrackate bottoms to the bottoms residue is between about 0.3/1 to4/1.

6. A method according to claim 4 wherein a portion of the convertedliquid products from the thermal conversion zone is treated to removeash solids from liquid products and the liquid products are recycled tothe process.

7. A method according to claim 6 wherein the recovered liquid productsare recycled to the thermal conversion zone.

8. A method according to claim 1 wherein said whole crude oil containscondensed ring aromatic hydrocarbons, the gas oil fractionated therefromand fed to said hydrocracking step contains condensed ring aromatichydrocarbons and the hydrocrackate bottoms contain at least 20 volumepercent condensed ring naphthene hydrocarbons.

9. A method according to claim 2 wherein said whole crude oil containscondensed ring aromatic hydrocarbons, the gas oil fractionated therefromand fed to said hydrocracking step contains condensed ring aromatichydrocarbons and the hydrocrackate bottoms contain at least 20 volumepercent condensed ring naphthene hydrocarbons.

10. A method according to claim 6 wherein the removal of ash solids isaccomplished by filtering.

References Cited by the Examiner UNITED STATES PATENTS 2,715,603 8/1955Lanning et al. 208-96 2,859,169 11/1958 Herman 208- 2,932,611 4/1960Scott et al. 208-80 3,019,180 1/ 1962 Schreiner et a1. 208--79 3,147,2069/ 1964 Tulleners 208--l 11 OTHER REFERENCES Advances in Petroleum Chem.and Refining, vol. III, Hydrogenation, Horne et al., pp. 215 to 217 and258. Interscience Pub. Inc., New York, 1960.

DELBERT E. GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

1. A METHOD OF TREATING WHOLE PETROLEUM CRUDE OILS TO RECOVER LOWERBOILING HYDROCARBONS WHICH COMPRISES FRACTIONATING A WHOLE PETROLEUMCRUDE OIL INTO A GAS OIL FRACTION AND A BOTTOMS RESIDUE, CATALYTICALLYHYDROCRACKING THE GAS OIL FRACTION TO PRODUCE LOWER BOILING HYDROCARBONSAND HIGHER BOILING HYDROGENATED DONOR DILUENTS, FRACTIONATING THEHYDROCRACKATE PRODUCT INTO NAPHTHA AND HYDROCRACKATE BOTTOMS CONTAININGHYDROGENATED DONOR DILUENTS, MIXING THE HYDROCRACKATE BOTTOMS WITH THEBOTTOMS RESIDUE AND MAINTAINING THE MIXTURE UNDER SUPERATMOSPHERICPRESSURE AT AN ELEVATED TEMPERATURE IN A THERMAL NON-CATALYTIC HDDCCONVERSION ZONE TO EFFECT HYDROGEN TRANSFER AND UPGRADING OF SAIDBOTTOMS RESIDUE TO NAPHTHA AND GAS OIL AND FRACTIONATING THE PRODUCTSFROM SAID THERMAL CONVERSION ZONE TO RECOVER ADDITIONAL GAS OILDISTILLATE AND NAPHTHA.